Missing at speed?

[dklawson]

A friend of mine pointed out another thing to check. On most of the Lucas distributors there is an earth/ground wire INSIDE the distributor. This goes between the breaker plate and the dizzy housing. It's typically a cloth insulated piece of high-flex fine stranded wire.

If that wire is missing, the coil current has to pass through the bearing in the breaker plate. This can create intermittent problems. It may work for days without issue and suddenly the engine might start surging or may even stop. You can't just go by "oh it looks like it's there", you need to give it a gentle tug to make sure it isn't broken beneath the insulation.

 

[mikespain]

sounds like you have a problem with some cable earthing out somewhere

 

[Darrel]

Thanks for all the help everyone.
I tried all the advice here - took off the belt and checked the bearings on the alternator (only done about 2000 mi). No issue. Same with the waterpump - new from the rebuild, so also only about 2000 miles old. No issues.

Removed all earth points - cleaned and tightened up. Removed fuse box and cleaned and wire tightened. Battery terminals checked and tightened.

Recently replaced the points and condensor with a Lumenition electronic module. That all checked out ok.

Leads me to think I may have a sticky valve? Any thoughts on this angle?

 

[Silverghost]

Could it still be a fuel supply issue? The lights going dim could be a side effect of the rpm drop when the engine drags. Did you run through the filter, etc.?

 

[dklawson]

Lumenition? Ok, I have one more long shot for you.

An acquaintance of mine on another board had problems with his ignition system after changing to Lumenition. As it turned out, he used the crimp terminals supplied with the Lumenition kit. Eventually he replaced the Lumenition terminals and all his ignition problems went away.

I know it's a long shot but it is an easy thing to try. Don't forget to try refitting the points and condenser again.

 

[mikespain]

I still recckon it is more than likely a wiring problem only way it can affect both ignition and lighting at same time,either a main earth lead not earthing properly or a power lead earthing out with movement of the engine,thus pulling the headlights and panel lights down,as it has an alternator the engine revs should not affect the output from the alternator so doubt fuel problem.if this has only started since you changed to lumenition then it could be something to do with the lumenition going down to earth.

 

[Darrel]

The problem was occuring before I changed to electronic ignition. So I do not think it is an issue with the ignition system. I have booked the car in with an auto electrician to check all the wiring et al for me. Will keep you posted.

 

[dklawson]

OK, so it's not the Lumenition then.

As Mike said, this really does point more to some weak or damaged electrical connection since you reported on 5/8 that the headlights were also affected. Of course... it could also be something failing in the alternator.

With an intermittent problem, bench testing the alternator may not reveal any problems. However, it sure sounds like it would be a good idea to check the wires to and from the alternator and be sure to check the battery cable where it exits the channel under the car (near the exhaust pipe). I know several people who's car died because this cable came out of the channel and shorted to the pipes.

Perhaps the uphill missing/surging you've got is the alternator kicking in/out as a connection is made or broken... particularly if its a short of the main battery cable.

 

[Darrel]

She was dead this morning. Just plain refused to start! Motor turned, by not even a hint of life. May be easier to trace the fault now... Will keep you posted

 

[dklawson]

DOH!!!

Do let us know what you find.

 

[Darrel]

Had a quick look when I got home. Tried to start her and she fired up! However, there was a loud clicking noise (best I can describe it) from the distributor. So turned off and popped the disi cap off. I seem to have a lot of up and down movement of the shaft - more than I think there should be. I would guess about 3 to 4 mm (0.11 to 0.16 in).

Am I correct? Is this too much movement? Should there be any? It is a Lucas 25D.

 

[dklawson]

Up and down movement? That seems a bit odd. The drive dog has shim washers to minimize the up/down freeplay of the shaft relative to the housing.

The 4-lobe cam is a separate part held onto the main dizzy spindle by a phillips head screw. Remove the rotor and you may or may not find a felt pad in the center of the 4-lobe cam. If you see the felt, pull it out and you should see the center screw. Tighten that screw and see if you still have motion up and down. You really shouldn't have much motion when that screw is tight.

If after tightening the screw you still have axial play in the dizzy I'd pull it out and go completely through it to see where it's coming from. I'm not sure how it would be related to your surging problem and it really should have no bearing on the headlights getting brighter or dimmer, but it's certainly something I would look at.

 

[Darrel]

Thanks Doug!
Your advice has been really helpful!
Will keep you posted.

 

[Darrel]

That screw could not be tightened anymore. So distributor was pulled and sent for repair. Will let you know when it is back - what the synopsis was.

 

[Darrel]

Distributor was repaired. They also bench tested it for me and found that the spark was not strong enough. Distributor was converted to electronic ignition about 4 months ago. Everything is working - the issue seems to be the ballast that Lumenition say must be in place. Without the ballast - spark is good. With ballast spark is poor.

Question: Can I run a Lumenition Magnetronic system without the ballast? Or with this damage the module?

 

[Darrel]

Distributor was repaired. They also bench tested it for me and found that the spark was not strong enough. Distributor was converted to electronic ignition about 4 months ago. Everything is working - the issue seems to be the ballast that Lumenition say must be in place. Without the ballast - spark is good. With ballast spark is poor.

Question: Can I run a Lumenition Magnetronic system without the ballast? Or will this damage the module?

 

[dklawson]

Lumenition is stuff I have not worked on. You may want to put posts about this in the Spridget and MG forums. The Mini, the Spridgets, and the MGB all use the same series of Lucas distributors so you're likely to find someone who can answer this there. Meanwhile, I'll post your question on a U.K. board I frequent since Lumenition is more common over there.

Can you type a bit of the Lumenition instructions that discuss the ballast? Typically the ignition system is expecting a total series resistance of some value. If you're using a low-resistance coil a ballast resistor is often added to bring the total resistance back in line.

 

[dklawson]

Interim Post:

Humor me by telling me some more about your car without my having to re-read the previous three pages of posts. What year is your Mini? What ignition is on the car (Lumenition Optronic with the optical chopper, or Magnetronic with the Hall Effect sensor)? What wires are on each coil terminal?

Please review the following.
(Optronic Lumenition)
https://www.lowflying.dk/images/PMA50ins.pdf
SUITABLE FOR coils or coil/ballast combinations of not less than 3 ohms.
NOT SUITABLE FOR use with low resistance (i.e. less than 1ohm) electronic ignition coils

(Magnetronic Lumenition)
https://www.lumenition.com/new/support/magign/mtk003_instructions_v1-3.pdf
No mention of ballast requirement

Some Minis in the early 1970s did have a ballast ignition system. Typically these had a pink/white resistor wire from the ignition switch to coil (+). They also had a yellow/white wire between the starter solenoid and coil (+). Does any of this sound like your car?

The notes on the Optronic kit are really important to interpret correctly. Note that they say your TOTAL series resistance (ballast + coil) should be 3 Ohms. This does not mean you necessarily have to run a ballast.

Write back and tell me a bit more about your car, its coil wiring, the coil you've fitted, and whether or not you've got a multimeter. If not... it's time to buy one.

 

[Darrel]

Hi Doug

You are quire right! I checked the insructions at home and when I did the install I misinterpreted the diagram to "have to include" the ballast. It is not necessary - unless it was previously ballasted. It is the magnetronic system.

The coil fitted is the Lumenition specced ans supplied coil. Coil was tested and is still strong.

It is a 1000cc Mini station wagon - 1968. There is no ballast wire. I do have a multimeter.

Hope I have answered all your questions. Its now time to get the distributor back in the car and back to the original problem - the reason for this lengthy thread!

 

[dklawson]

I'm not familiar with Lumenition's coils. However, with NO wires connected to it, use your multimeter to measure across its low tension terminals. If you find close to 3 Ohms... you're golden and don't need the ballast.

This may be why the car refused to start last week. If you have a 3 Ohm coil and you added a ballast resistor in series with it, the amount of current flowing through the coil will be significantly reduced. This would be true at highway speeds also. Even though you say the misfire happened with points... test drive the car for a while without the ballast resistor and see if it's better.